Copyright is an interesting creature....worthwhile for all to educate oneself.
Intellectual property has an owner.
That owner owns the right to determine exactly how his property is distributed to one and all.
When a skinner has reached the status/level of MASTER he has the opportunity to release his works as Master skins on Wincustomize for commercial sale.
That means there is a simple commercial contract between the supplier [Master] aka vendor and the recipient aka purchaser.
A fee is involved in that transaction. Under International Copyright Law that means the purchaser has obtained rights to use the product purchased.
It DOES NOT MEAN he also has purchased the right to distribute that product [freely or otherwise] to others.
THAT is an actual breach of copyright.
Stardock and Wincustomize will not tolerate any such transgressions of copyright law.
If you think ANY works here are great...tell the author....tell the world...but please remember you do not have legal authority to distribute them. Only their author can give you such permission.